Two parallel efforts, now underway, will be continued in this third year of a 3-year grant. First, the geometrical and hydrodynamic aspects of apparatus designed to handle flowing blood will be explored with two devices now available (capillary flow unit and rotating-disk unit). By means of using a variety of special capillaries--having different inlet features, L/D ratios, diameters, tapers, etc.--the pressure-driven capillary blood flows will be evaluated for hemolytic potential. Existing data on the disk system will also be analyzed. The focus will be on the low-stress laminar flows encountered in practice, and the intent is to develop predictive capabilities with these design features analogous to that already developed here with biomaterials. The second type of effort is chemical/hematological, extending our recent findings on blood additives which suppress mechanical hemolysis to (a) seek understanding the the basic processes--e.g., erythrocyte membrane alterations--by which these additives function, (b) exlpore the suitability of the additives for non-flow storage purposes, and (c) discover other agents with similar or superior properties. Shear-flow testing will be supported by erythrocyte characterization with microscopy and resistive pulse spectroscopy.